My cousin sends me essays he writes for his English classes. I edit them for fun. Take a wild guess as to how I feel about grammar.

That aside, I try not to force anything on other people, especially online. Unless someone's grammar and spelling is so absolutely terrible that I cannot understand what he or she is saying, I don't feel the need to point out trivial mistakes. It does, however, take a conscious effort not to make such corrections; sometimes I slip.